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Brodsky said she hoped to include Afghanistan, but that became impossible because of the threat of violence and social barriers. Producer Tom Grant had to wear a bulletproof vest while filming in the war-torn country.

He was unable to capture compelling footage because of familial protocol that forbids a man from entering a home full of women while no husband is present. Thus, Grant was often denied access, Brodsky said.

In many countries, people are hesitant to vaccinate their children against polio because of a distrust of the government. Some civilians believe the vaccination to be "something more sinister like a sterilizing drug" produced to curtail their population, Brodsky explained.

She said she often ran into "the skepticism that some communities have against our government in cooperation with their own government."

"It never occurred to me that U.S. foreign policies could affect young children living in the most densely populated areas," she said.

Although it has been 50 years since the United States developed a vaccination for polio, millions of children abroad remain unprotected.

"Ordinary American people have forgotten polio," Brodsky said. And, although the number of polio cases have been reduced by 99 percent, the highly infectious disease is still very real.

"It really limits the opportunities a child might have as an adult," said Oliver Rosenbauer, a spokesman for the World Health Organization's Global Polio Eradication Initiative.

As part of the Global Polio Eradication Initiative, 20 million volunteers deliver vaccinations to schools, bus stops and rail stations across the world on a daily basis.

Only four countries had recorded cases of polio in 2008, down from 125 countries 10 years ago, according to the Global Polio Eradication Initiative.